Multi-tube once-through boiler

ABSTRACT

In a multi-tube once-through boiler configured such that boiler water within water tubes is heated and evaporated to take out consumed steam, rows of water tubes arranged on the left and right of the combustion chamber are respectively connected by linear left and right upper headers provided at upper ends and linear left and right lower headers provided at lower ends, a lid body is formed on one end side facing the combustion chamber and a burner for supplying combustion gas to the combustion chamber is provided, and the burner is provided with a recovered oil supply unit for supplying recovered oil, a waste solvent supply unit for supplying a waste solvent, an injected air supply unit, a combustion air supply unit, and a control unit for controlling the supply of the recovered oil, the waste solvent, the injected air, and the combustion air.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a Section 371 National Stage Application of International Application No. PCT/JP2019/010813, filed on Mar. 15, 2019, and published as WO 2020/188625 A1, on Sep. 24, 2020, not in English, and entitled “MULTI-TUBE ONCE-THROUGH BOILER”, the contents of which are incorporated herein by reference in their entireties.

TECHNICAL FIELD

The present invention relates to a multi-tube once-through boiler that generates steam by heating a large number of water tubes, and more particularly to a structure of a multi-tube once-through boiler in which recovered oil can be used as fuel.

BACKGROUND ART

In the multi-tube once-through boiler, as shown in FIG. 10 and FIG. 11 disclosed in Patent Document 1 for example, a plurality of water tubes are vertically arranged in a cylindrical combustion cylinder with upper and lower bottoms, an annular upper header 1 and lower header 2 are connected by two rows of water tubes of an inner water tube row 3 and an outer water tube row 4, and gaps between adjacent water tubes of the inner water tube row 3 and adjacent water tubes of the outer water tube row 4 are blocked (blocking fins 8).

Further, by opening a part between the water tubes in the inner water tube row 3 (inner smoke passage port 5), a combustion gas passage 7 is formed between the inner water tube row 3 and the outer water tube row 4, and boiler water is configured to be supplied to each water tube from the lower header 2.

In the above structure, the multi-tube once-through boiler is configured such that, by supplying fuel to a burner 10 installed within the combustion cylinder and burning the fuel, combustion gas is generated in a combustion chamber 9, the combustion gas is supplied from the combustion gas passage 7 to the outside of the plurality of water tubes to heat and evaporate the boiler water within the water tubes, and consumed steam is taken out from the upper header 1.

Further, the combustion gas passes through the combustion gas passage 7 and an outer smoke passage port 6 and is discharged from a flue 12 as combustion exhaust gas whose temperature is lowered.

Peripheral parts of the upper header 1 and the lower header 2 are covered with a refractory material 13, and the entire combustion cylinder is covered with a heat insulating material 14.

CITATION LIST Patent Document

Patent Document 1: Japanese Patent No. 2914647

SUMMARY OF INVENTION Technical Problem

However, according to the foregoing multi-tube once-through boiler, because of a structure such that the combustion chamber 9 is sealed and cleaning etc. of the inside of the combustion cylinder is difficult, there is a problem that the combustion gas to be burned is limited and waste oil and the like in which residual ash is easily generated cannot be used.

Further, cleaning is performed for impurities contained in water adhering to the inside of the water tubes by using chemicals for washing, but there is a problem that a sufficient washing effect cannot be obtained.

The present invention has been made in view of the foregoing circumstances, and an object thereof is to provide a multi-tube once-through boiler in which waste oil can be used as combustion gas for generating consumed steam and cleaning of water tubes can be performed easily.

In order to achieve the above object, the present invention (claim 1) is a multi-tube once-through boiler configured such that both end sides of each of a plurality of water tubes communicate with each other and boiler water is supplied to each water tube, while a combustion chamber is formed inside each water tube, combustion gas from the combustion chamber is supplied outside the plurality of water tubes to heat and evaporate the boiler water within the water tubes, and consumed steam is taken out, wherein the combustion chamber has a horizontally extending cylindrical shape,

each water tube has an arc shape arranged on left and right sides of the combustion chamber,

a row of water tubes arranged on the left side of the combustion chamber are respectively connected by a linear left upper header (1L) provided at an upper end and a linear left lower header (2L) provided at a lower end,

a row of water tubes arranged on the right side of the combustion chamber are respectively connected by a linear right upper header (1R) provided at an upper end and a linear right lower header (2R) provided at a lower end,

a door (lid body 22) is formed on one end side facing the combustion chamber and a burner installed on an outer surface of the door and supplying combustion gas to the combustion chamber is provided,

the burner is provided with a recovered oil supply unit supplying recovered oil, a waste solvent supply unit for supplying a waste solvent,

an injected air supply unit for supplying injected air for spraying the recovered oil and the waste solvent in the burner,

a combustion air supply unit for supplying combustion air for burning the recovered oil and the waste solvent in the burner, and

a control unit for controlling supply of the recovered oil, the waste solvent, the injected air, and the combustion air.

Claim 2 is the multi-tube once-through boiler according to claim 1, wherein the rows of water tubes are each composed of an inner water tube row and an outer water tube row, and each water tube of the outer water tube rows is arranged between water tubes of the inner water tube rows.

Claim 3 is the multi-tube once-through boiler according to claim 1, wherein an openable and closable hole portion is formed in each front surface on the door (lid body 22) side of the left upper header (1L) and the right upper header (1R) and each front surface on the door (lid body 22) side of the left lower header (2L) and the right lower header (2R).

Claim 4 is the multi-tube once-through boiler according to claim 2, wherein a group of rows of water tubes composed of the inner water tube rows and the outer water tube rows is arranged so that the door (lid body 22) side is located at a lower position than the innermost side of the combustion chamber.

Effects of Invention

According to claim 1, the combustion chamber has a horizontally extending cylindrical shape and the door (lid body 22) is formed on one end side facing the combustion chamber, whereby the inside can be faced by opening and closing operation of the door (lid body 22) and the combustion chamber can be cleaned easily. As a result, waste oil can be used as combustion fuel.

Further, the recovered oil and the waste solvent are adjusted in injection amount and mixed in the burner using an injection unit and an injection unit, whereby the recovered oil and the waste solvent can be burned efficiently.

As a result, the recovered oil and the waste solvent, which are waste agents, can be used as fuel, so that fuel costs can be reduced.

According to claim 2, by arranging each water tube of the outer water tube rows between the water tubes of the inner water tube rows, a large number of water tubes can be stored compactly.

According to claim 3, by providing the openable and closable hole portion (screw lid 25) in the upper header and the lower header, cleaning of the inside of each water tube using a liquid can be performed easily.

According to claim 4, by angling the group of rows of water tubes composed of the inner water tube rows and the outer water tube rows, fluid can be made to flow easily and the liquid can be prevented from remaining in each water tube at the time of washing.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front explanatory diagram showing a multi-tube once-through boiler according to one embodiment of the present invention.

FIG. 2 is a right-side explanatory diagram showing the multi-tube once-through boiler according to one embodiment of the present invention.

FIG. 3 is a left-side explanatory diagram showing the multi-tube once-through boiler according to one embodiment of the present invention.

FIG. 4 is an explanatory diagram of a configuration of a peripheral part of a burner in the multi-tube once-through boiler

FIG. 5 is a front explanatory diagram of inner water tube rows and outer water tube rows of the multi-tube once-through boiler.

FIG. 6 is a partial cross-sectional explanatory diagram showing a connection structure between upper headers and inner water tubes and outer water tubes of the multi-tube once-through boiler.

FIG. 7 is a side explanatory diagram showing the inner water tube row and the outer water tube row of the multi-tube once-through boiler.

FIG. 8 is a plan explanatory diagram showing an example of a flow passage of combustion gas in a main body of the multi-tube once-through boiler.

FIG. 9 is a plan explanatory diagram showing another example of the flow passage of combustion gas in the main body of the multi-tube once-through boiler.

FIG. 10 is an explanatory diagram of a configuration showing a schematic structure of a conventional multi-tube once-through boiler.

FIG. 11 is a cross-sectional explanatory diagram taken along line A-A in FIG. 10.

DESCRIPTION OF THE EMBODIMENTS

One embodiment of a multi-tube once-through boiler of the present invention will be described with reference to the drawings.

FIG. 1 to FIG. 3 show the appearance of the multi-tube once-through boiler, wherein a lid body 22 serving as a door for opening and closing the front side of a cylindrical main body 20 arranged sideways is rotatably attached to a hinge portion 21 attached to the main body 20. A burner 10 is installed on an outer surface of the lid body 22, and fuel is supplied to the burner 10 and burned, thereby generating combustion gas in a combustion chamber 9 inside the main body 20.

By heating a plurality of water tubes installed inside the main body 20 from the outside, the combustion gas generated in the combustion chamber 9 of the main body 20 heats and evaporates boiler water within the water tubes to generate steam (consumed steam) and is carried out as combustion exhaust gas from a flue 12 provided on an upper part of the main body 20.

Next, the peripheral structure of the burner 10, which is a characteristic configuration of the present invention, will be described with reference to FIG. 4 and FIG. 3.

The burner 10 is provided with a recovered oil supply unit 100 for supplying recovered oil, a waste solvent supply unit 200 for supplying a waste solvent, an injected air supply unit 300 for supplying injected air for spraying the recovered oil and the waste solvent in the burner 10, and a combustion air supply unit 400 for supplying combustion air for burning the recovered oil and the waste solvent in the burner 10.

Used engine oil etc. is used as the recovered oil. The recovered oil supplied from the recovered oil supply unit 100 is supplied at a flow rate of 25 to 90 L/H when the amount of steam generated per hour is for 2 tons, and further is adjusted in the supply amount through the fuel control pump 101 and is guided to the injection unit 102.

By-product oil is used as the waste solvent, and gutter oil (recycled edible oil), waste ink, etc. are included therein. The waste solvent that can be used as the by-product oil includes all industrial waste of solvents conventionally disposed of. The waste ink is an ink etc. to be disposed of that is generated when washing an ink adhering to a rotary press at the time of changing the color of printing in the rotary press, for example.

The waste solvent supplied from the waste solvent supply unit 200 is supplied at a flow rate of 20 to 50 L/H when the amount of steam generated per hour is for 2 tons, and further is adjusted in the supply amount according to the type of waste solvent through a fuel control pump 201 and is guided to an injection unit 202.

The high-pressure air (0.6 to 0.7 MPa) supplied from the injected air supply unit 300 is branched into two systems, each adjusted in pressure by a pressure control unit 301, and guided to an injection unit (compressor) 102 or an injection unit (compressor) 202.

In the injection unit 102, a predetermined supply amount (in this example, 25 to 90 L/H) of recovered oil and air of a predetermined pressure (2 to 3 kgf/cm²) are mixed, whereby the recovered oil is sprayed in a mist form and guided into the burner 10. The supply amount is adjusted according to the type of recovered oil.

In the injection unit 202, a predetermined supply amount (in this example, 20 to 50 L/H) of waste solvent and air of a predetermined pressure (2 to 3 kgf/cm²) are mixed, whereby the waste solvent is sprayed in a mist form and guided into the burner 10. The supply amount is adjusted according to the type of waste solvent.

In the burner 10, the recovered oil and waste solvent sprayed in the mist form and combustion air supplied from the combustion air supply unit (blower) 400 through a flow rate control unit 401 guide the recovered oil and the waste solvent into the main body 20 and burn them.

Further, the burner 10 is provided with an ignition unit 500 and is configured to maintain combustion after igniting the recovered oil, waste solvent, and combustion air supplied into the burner 10 with LPG gas.

With the above configuration, combustion can be efficiently performed in the main body 20 by adjusting the supply amounts of the recovered oil and the waste solvent and mixing them in a spraying state using the injection unit 102 and the injection unit 202.

The recovered oil and the waste solvent can be used as boiler fuel, so that fuel costs can be reduced.

Further, the used engine oil used as the recovered oil has zero carbon dioxide emissions (already converted when used as engine oil), so that such a calculation that the carbon dioxide emissions increase is not made even if the used engine oil is used as boiler fuel. Thus, the used engine oil can be utilized effectively as fuel.

Subsequently, the internal structure of the main body 20 of the multi-tube once-through boiler will be described with reference to FIG. 5 to FIG. 8.

In the center of the main body 20, a horizontally extending cylindrical combustion chamber 9 is formed and a plurality of arc-shaped water tubes are arranged so as to surround the periphery of the combustion chamber 9.

Of the plurality of arc-shaped water tubes, a group of water tubes arranged on the left inner side of the combustion chamber 9 is defined as an inner water tube row 3L, and each upper end is connected by a linear left upper header 1L and each lower end is connected by a linear left lower header 2L. Similarly, a group of water tubes arranged on the right inner side of the combustion chamber 9 is defined as an inner water tube row 3R, and each upper end is connected by a linear right upper header 1R and each lower end is connected by a linear right lower header 2R. Further, gaps between the water tubes constituting the left and right inner water tube rows 3L, 3R are connected by blocking fins 8.

Further, the entire main body 20 of the multi-tube once-through boiler is covered with a heat insulating material 14.

Further, near an end portion of the inner water tube row 3 into which the combustion gas is injected inside the main body 20, the combustion chamber 9 installed with a collision wall 30 composed of a thick refractory material is formed. By providing an inner annular partition wall 15 between the inner water tube row 3 and the collision wall 30, the combustion gas injected from the burner 10 is configured to all flow back after colliding with the collision wall 30.

Outside the inner water tube row 3, water tubes arranged between the water tubes of the inner water tube row 3 are arranged and a group of these water tubes constitutes an outer water tube row 4. The outer water tube rows 4 are each arranged outside the left and right inner water tube rows 3. Similar to the left and right inner water tube rows 3, each upper end of the left group of water tubes is connected to the left upper header 1L and each lower end thereof is connected to the left lower header 2L, and each upper end of the right group of water tubes is connected to the right upper header 1R and each lower end is connected to the right lower header 2R. Gaps between the water tubes constituting the left and right outer water tube rows 4 are connected by the blocking fins 8 similar to the inner water tube rows 3.

On the combustion gas supply side (lid body 22 side), an inner smoke passage port 5 is formed between an inner wall of the lid body 22 and the end water tubes, and a notch (inner smoke passage port 5A) is formed on the blocking fins 8 connecting the water tubes of the inner water tube row 3. That is, as shown in FIG. 7, the notches (hatched portions) are each formed on three blocking fins 8 from the lid body 22 side.

The notches are formed by three-step openings in which their notch areas become the largest on the lid body 22 side. This makes it easy for the combustion gas colliding with the collision wall 30 and flowing back to return to the vicinity of the lid body 22 side by enlarging the notch at the position near the outlet of the combustion gas of the burner 10 (see FIG. 7).

Further, by providing an outer annular partition wall 16 capable of abutting against an inner surface of the lid body 22 at an end portion of the outer water tube row 4, the combustion gas flowing back to the lid body 22 side is configured to be guided between the inner water tube row 3 and the outer water tube row 4 and flow toward the collision wall 30 side outside the annular partition wall 15.

Lower surfaces of the left lower header 2L and the right lower header 2R are each provided with a water supply port 23, and upper surfaces of the left upper header 1L and the right upper header 1R are each provided with a steam discharge port 24.

Further, the group of rows of water tubes composed of the inner water tube rows 3 (left inner water tube row 3L and right inner water tube row 3R) and the outer water tube rows 4 (left outer water tube row 4L and right outer water tube row 4R) is inclined and arranged within the main body 20 so that the lid body (door) 22 side is at a lower position than the innermost side. The inclination angle is preferably about 5 degrees, for example.

A screw lid 25 is attached to the lid body (door) 22 side of the upper headers 1L, 1R and the lower headers 2L, 2R. By removing the screw lids 25, hole portions can be opened in the upper headers and the lower headers.

Washing water is supplied from the hole portions on the upper header 1L, 1R side and discharged from the hole portions on the lower header 2L, 2R side, whereby the inside of each water tube can be washed. At this time, since the lid body (door) 22 side is arranged at a position lower than the innermost side, the water for washing the inside of the water tube can be easily discharged from the hole portions on the lower header 2L, 2R side.

With the above structure, when water is supplied from each of the water supply ports 23 of the left lower header 2L and the right lower header 2R, the boiler water is supplied to each of the plurality of water tubes arranged in an arc shape, and when the combustion gas is supplied from the burner 10 to the combustion chamber 9, the combustion gas from the combustion chamber 9 comes into contact with an inner surface (surface on the combustion chamber 9 side) of each water tube of the inner water tube rows 3 to heat the boiler water within the water tubes.

The combustion gas is bounced back by the collision wall 30 installed at an end portion of the combustion chamber 9 and returned to the lid body 22 side, and as shown in FIG. 8, is guided from the inner smoke passage port 5 and the notches (inner smoke passage ports 5A) to a combustion gas passage 7A between the inner water tube row 3 and the outer water tube row 4 and comes into contact with the inner surfaces of the inner water tube row 3 and the inner surface of the outer water tuber row 4 to heat the boiler water within the water tubes.

The boiler water within the water tubes of the inner water tube rows 3 and the outer water tube rows 4 are heated to become steam, which is taken out as consumed steam from the steam discharge ports 24 provided to the left upper header 1L and the right upper header 1R and is consumed at a desired supply place.

The combustion gas is lowered in temperature by heating the boiler water within the water tubes and is discharged outside from the flue 12.

According to the structure of the multi-tube once-through boiler having the above structure, it becomes possible to use waste oil as combustion fuel for the burner 10.

That is, the lid body (door) 22 can be formed on one end side facing the combustion chamber 9 by forming the combustion chamber 9 into the horizontally extending cylindrical shape, so that the inside of the combustion chamber 9 can be opened by opening and closing operation of the lid body (door) 22.

Therefore, even when the combustion chamber 9 is contaminated with impurities by using the waste oil as fuel for the combustion gas, the inside can be easily cleaned to remove the impurities from the side by being opened.

Further, the recovered oil is injected from the injection unit 102, the waste solvent is injected from the injection unit 202, and they are adjusted in injection amount and mixed in the burner 10, whereby the recovered oil and the waste solvent can be burned efficiently.

As a result, the recovered oil and the waste solvent, which are waste agents, can be used as fuel, so that fuel costs can be reduced.

FIG. 9 shows another embodiment of the multi-tube once-through boiler, which is an example in which the forming position of the notches serving as the inner smoke passage ports is different from that of FIG. 8. That is, in the multi-tube once-through boiler of FIG. 9, the water tubes of the inner water tube rows 3 and the outer water tube rows 4 are connected by the blocking fins 8, and notches (inner smoke passage ports 5B) are each formed on three blocking fins 8 on both sides of the combustion gas supply side (lid body 22 side) of the outer water tube rows 4. Other configurations are the same as those of the multi-tube once-through boiler of FIG. 5 to FIG. 8.

With this configuration, the combustion gas injected from the burner 10 to the combustion chamber 9, bounced back by the collision wall 30 at the end portion, and returned to the lid body 22 side is, as shown in FIG. 9, guided from the inner smoke passage port 5 to the combustion gas passage 7A between the inner water tube row and the outer water tube row, and also guided from the notches (inner smoke passage ports 5B) to a combustion gas passage 7B between the outer water tube row 4 and an outer wall of the main body 20 (outer wall of the boiler), and comes into contact with outer surfaces on both sides of each water tube of the outer water tube row 4 to heat the boiler water within the water tubes. Therefore, this configuration acts on each water tube of the outer water tube row 4 in a manner that the contact area heated by the combustion gas is increased, so that each water tube of the outer water tube row 4 can be heated efficiently.

REFERENCE SIGNS LIST

1 . . . upper header

2 . . . lower header

4,4L,4R . . . outer water tube rows

5,5A,5B . . . inner smoke passage port

6 . . . outer smoke passage port

7,7A,7B . . . combustion gas passage

8. . . blocking fins

9 . . . combustion chamber

10 . . . burner

12 . . . flue

13 . . . refractory material

14 . . . heat insulating material

15 . . . inner annular partition wall

16 . . . outer annular partition wall

20 . . . main body

21 . . . hinge portion

22 . . . lid body (door)

23 . . . water supply port

24 . . . steam discharge port

25 . . . screw lid (hole portion)

30 . . . collision wall

100 . . . recovered oil supply unit

101 . . . fuel control pump

102 . . . injection unit (compressor)

200 . . . waste solvent supply unit

201 . . . fuel control pump

202 . . . injection unit (compressor)

300 . . . injected air supply unit

301 . . . pressure control unit

400 . . . combustion air supply unit

401 . . . flow rate control unit

500 . . . ignition unit 

1. A multi-tube once-through boiler configured such that both end sides of each of a plurality of water tubes communicate with each other and boiler water is supplied to each water tube, while a combustion chamber is formed inside each water tube, combustion gas from the combustion chamber is supplied outside the plurality of water tubes to heat and evaporate the boiler water within the water tubes, and consumed steam is taken out, wherein the combustion chamber has a horizontally extending cylindrical shape, each water tube has an arc shape arranged on left and right sides of the combustion chamber, a row of water tubes arranged on the left side of the combustion chamber are connected by a linear left upper header provided at an upper end and a linear left lower header provided at a lower end, a row of water tubes arranged on the right side of the combustion chamber are connected by a linear right upper header provided at an upper end and a linear right lower header provided at a lower end, a door is formed on one end side facing the combustion chamber and a burner installed on an outer surface of the door and supplying combustion gas to the combustion chamber is provided, the burner is provided with a recovered oil supply unit for supplying recovered oil including at least used engine oil, a waste solvent supply unit for supplying by-product oil as a waste solvent, an injected air supply unit for supplying injected air for spraying the recovered oil and the waste solvent in the burner at appropriate pressures each adjusted through a pressure control unit, a combustion air supply unit for supplying combustion air for burning the recovered oil and the waste solvent in the burner, and a control unit for controlling supply of the recovered oil, the waste solvent, the injected air, and the combustion air, and both the recovered oil and the waste solvent are used for fuel to operate.
 2. The multi-tube once-through boiler according to claim 1 wherein the rows of water tubes are each composed of an inner water tube row and an outer water tube row, and each water tube of the outer water tube rows is arranged between water tubes of the inner water tube rows.
 3. The multi-tube once-through boiler according to claim 1, wherein an openable and closable hole portion is formed in each front surface on the door side of the left upper header and the right upper header and each front surface on the door side of the left lower header and the right lower header.
 4. The multi-tube once-through boiler according to claim 2, wherein a group of rows of water tubes composed of the inner water tube rows and the outer water tube rows is arranged so that the door side is located at a lower position than the innermost side of the combustion chamber.
 5. The multi-tube once-through boiler according to claim 1, wherein the by-product oil is gutter oil.
 6. The multi-tube once-through boiler according to claim 1, wherein the by-product oil is waste ink. 